[ROVERNET - UK] Re:Rough running SD1

Dermot Harvey roverman2 at verizon.net
Wed Oct 10 15:42:27 BST 2007

My first guess would be partially clogged fuel injectors, but it's  
worth checking your fuel line pressure first. Find an old mechanical  
oil pressure gauge. Depressurize the system and attach the oil  
pressure gauge to the cold start fuel injector. Take the hose from  
the air filter to the airflow meter off. Stick a rag in the airflow  
meter. This will turn on the fuel pump when the ignition is on. You  
should get a steady reading of about 40 psi. Turn the ignition off  
and watch how slowly the pressure drops - the longer it takes the  
If your fuel pressure is OK you should remove the fuel injectors and  
test them for flow rate and spray pattern. This is a messy procedure.  
I have a test rig using an old  fuel pump and pressure regulator. The  
injectors should deliver 125 to 150 ml per minute and you should have  
a conical spray pattern. You might be able to find a shop that has  
testing and cleaning equipment for fuel injectors. Sometimes the  
injectors can be cleaned.If not you can buy new or rebuilt ones.
Before you put everything back together, be sure your fuel filters  
are reasonably new and carefully check the rubber fuel lines. If  
there is any sign of checking or cracking you should replace the  
rubber lines making sure only to use high pressure fuel injection hose.
The other possibility is that your ignition module is faulty. I think  
by now most people are using Lumenition or Pertronix modules, but if  
you have the original module inside the distributor it has probably  
about had it.

Good Luck!

Dermot Harvey
Spectral Kinetics

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